* To evaluate the effect of combination therapy with HIVIG (administered every 28 days until delivery beginning between 20-30 weeks of pregnancy and to the newborn within 12 hours of birth), and ZDV (administered intrapartum and to the newborn for 6 weeks), compared to IVIG and ZDV, administered similarly, on the transmissin of HIV infection to infants born to HIV-infected women. All women in this study are receiving ZDV for medical indications. * To evaluate maternal virologic and immunologic factors involved in HIV transmission from mother to infants, and the influence of HIVIG on the parameters.